How to save detected face in Android using OpenCV?

Question

I am using OpenCV's sample code to detect face with android device. I want to save only detected face area to sd card. I am trying to convert mat to Bitmap and save it. But my problem is it saves whole image rather than just Face. here's my method to convert mat to bitmap

Bitmap bitmap = Bitmap.createBitmap(mGray.cols(), mGray.rows(), Bitmap.Config.ARGB_8888);
        Utils.matToBitmap(mGray, bitmap);

        String root = Environment.getExternalStorageDirectory().toString();
        File myDir = new File(root + "/saved_images");    
        myDir.mkdirs();
        Random generator = new Random();
        int n = 10000;
        n = generator.nextInt(n);
        String fname = "Image-"+ n +".jpg";
        File file = new File (myDir, fname);
        if (file.exists ()) file.delete (); 
        try {
               FileOutputStream out = new FileOutputStream(file);
               bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
               out.flush();
               out.close();

        } catch (Exception e) {
               e.printStackTrace();

I am a beginner with Opencv. Please help. Thank you in advance

Answer 1

The problem is, you are never trying to get the face pixels. After you detect face, I suggest you to do something such as:

Mat mFaceMatrix = mRgba.submat(facesArray.y, facesArray.y + facesArray.heigth, facesArray.x, facesArray.x + facesArray.width);

Now passing this matrix to createBitmap function should do the trick.

Bitmap bitmap = Bitmap.createBitmap(mFaceMatrix.cols(), mFaceMatrix.rows(), Bitmap.Config.ARGB_8888);
Utils.matToBitmap(mFaceMatrix, bitmap);